991541 has 2 divisors, whose sum is σ = 991542. Its totient is φ = 991540.

The previous prime is 991531. The next prime is 991547. The reversal of 991541 is 145199.

991541 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 970225 + 21316 = 985^2 + 146^2 .

It is a cyclic number.

It is not a de Polignac number, because 991541 - 2¹⁴ = 975157 is a prime.

It is a Chen prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991541.

It is not a weakly prime, because it can be changed into another prime (991547) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495770 + 495771.

It is an arithmetic number, because the mean of its divisors is an integer number (495771).

2⁹⁹¹⁵⁴¹ is an apocalyptic number.

It is an amenable number.

991541 is a deficient number, since it is larger than the sum of its proper divisors (1).

991541 is an equidigital number, since it uses as much as digits as its factorization.

991541 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1620, while the sum is 29.

The square root of 991541 is about 995.7615176336. The cubic root of 991541 is about 99.7172345238.

The spelling of 991541 in words is "nine hundred ninety-one thousand, five hundred forty-one".